Drain the canned tuna and gently squeeze it to remove any excess liquid.

In a mixing bowl, combine the drained tuna, Kewpie mayonnaise, sriracha, lemon juice, and toasted sesame oil. Stir until blended well and creamy.

In a large bowl, add the cooked sushi rice followed by the spicy tuna mixture, diced cucumbers, and avocado. Toss until evenly mixed.

Drizzle with additional mayonnaise and sriracha as desired. Top with sliced green onions and sprinkle with roasted sesame seeds.